Polimorfizm –455G/A genu β-fibrynogenu a ryzyko udaru niedokrwiennego w populacji polskiej

Background and purpose Ischaemic stroke is considered to be multifactorial and interactions between environmental and genetic factors play an important role. Although vascular risk factors are well known, the genetic ones are still undiscovered. In the present study, we assessed the significance of the β-fibrinogen –455G/A gene polymorphism and the risk of ischaemic stroke in a Polish population. Material and methods 426 ischaemic stroke patients classified according to stroke aetiologies (small vessel disease, large vessel disease or cardioembolic stroke) and 234 controls were included in the study. The association of the β-fibrinogen genotypes with ischaemic stroke was tested using logistic regression analysis under dominant, recessive or additive models of inheritance. Results The allele and genotype distributions of the β-fibrinogen –455G/A gene polymorphism did not differ significantly between patients and controls (patients: G – 75%, GG – 56.6%, GA – 36.8%, AA – 6.6%; controls: G – 73.7%, GG – 57.3%, GA – 32.9%, AA – 9.8%; p > 0.05, χ2). In addition, logistic regression analysis adjusted for the known risk factors, i.e. hypertension, ischaemic heart disease, myocardial infarction, hypercholesterolaemia, diabetes mellitus and smoking, did not show a role of the studied polymorphism in ischaemic stroke. Conclusions The β-fibrinogen –455G/A gene polymorphism is not a risk factor for ischaemic stroke in a Polish population.Wstęp i cel pracy Etiologia udaru niedokrwiennego mózgu jest wieloczynnikowa. Istotną rolę odgrywają w niej interakcje pomiędzy czynnikami środowiskowymi i genetycznymi. Naczyniowe czynniki ryzyka udaru mózgu są dość dobrze poznane, natomiast rola czynników genetycznych pozostaje wciąż niejasna. W prezentowanym badaniu oceniano znaczenie polimorfizmu –455G/A genu β-fibrynogenu w kontekście ryzyka wystąpienia udaru niedokrwiennego mózgu w populacji polskiej. Materiał i metody Do badania włączono 426 chorych na udar niedokrwienny mózgu sklasyfikowanych zgodnie z etiologią udaru (choroba małych naczyń, choroba dużych naczyń lub udar sercowozatorowy) oraz 234 osoby z grupy kontrolnej. Związek pomiędzy badanym polimorfizmem a udarem niedokrwiennym mózgu został zbadany przy użyciu regresji logistycznej w dominującym, recesywnym i addytywnym modelu dziedziczenia. Wyniki Nie stwierdzono istotnej różnicy w rozkładzie alleli i genotypów polimorfizmu –455G/A genu β-fibrynogenu pomiędzy pacjentami a osobami z grupy kontrolnej (pacjenci: G – 75%, GG – 56,6%, GA – 36,8%, AA – 6,6%; grupa kontrolna: G – 73,7%, GG – 57,3%, GA – 32,9%, AA – 9,8 %; p > 0,05, test χ2). Ponadto w modelu regresji logistycznej uwzględniającym wpływ znanych czynników ryzyka, takich jak: nadciśnienie tętnicze, choroba niedokrwienna serca, zawał mięśnia sercowego, hipercholesterolemia, cukrzyca i palenie tytoniu, nie wykazano roli badanego polimorfizmu w udarze niedokrwiennym mózgu. Wnioski Polimorfizm –455G/A genu β-fibrynogenu nie jest czynnikiem ryzyka udaru niedokrwiennego mózgu w populacji polskiej

Search for fibrous aggregates potentially useful in regenerative medicine formed under physiological conditions by self-assembling short peptides containing two identical aromatic amino acid residues

This study investigates the propensity of short peptides to self-organize and the influence of aggregates on cell cultures. The dipeptides were derived from both enantiomers of identical aromatic amino acids and tripeptides were prepared from two identical aromatic amino acids with one cysteine or methionine residue in the C-terminal, N-terminal, or central position. The formation or absence of fibrous structures under physiological conditions was established using Congo Red and Thioflavine T assays as well as by microscopic examination using normal and polarized light. The in vitro stability of the aggregates in buffered saline solution was assessed over 30 days. Materials with potential for use in regenerative medicine were selected based on the cytotoxicity of the peptides to the endothelial cell line EA.hy 926 and the wettability of the surfaces of the films, as well as using scanning electron microscopy. The criteria were fulfilled by H-dPhedPhe-OH, H-dCysdPhedPhe-OH, H-CysTyrTyr-OH, H-dPhedPhedCys-OH, H-TyrTyrMet-OH, and H–TyrMetTyr–OH. Our preliminary results suggest that the morphology and cell viability of L919 fibroblast cells do not depend on the stereochemistry of the self-organizing peptides

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

A ubiquitous biological material, keratin represents a group of insoluble, usually high-sulfur content and filament-forming proteins, constituting the bulk of epidermal appendages such as hair, nails, claws, turtle scutes, horns, whale baleen, beaks, and feathers. These keratinous materials are formed by cells filled with keratin and are considered 'dead tissues'. Nevertheless, they are among the toughest biological materials, serving as a wide variety of interesting functions, e.g. scales to armor body, horns to combat aggressors, hagfish slime as defense against predators, nails and claws to increase prehension, hair and fur to protect against the environment. The vivid inspiring examples can offer useful solutions to design new structural and functional materials. Keratins can be classified as α- and β-types. Both show a characteristic filament-matrix structure: 7 nm diameter intermediate filaments for α-keratin, and 3 nm diameter filaments for β-keratin. Both are embedded in an amorphous keratin matrix. The molecular unit of intermediate filaments is a coiled-coil heterodimer and that of β-keratin filament is a pleated sheet. The mechanical response of α-keratin has been extensively studied and shows linear Hookean, yield and post-yield regions, and in some cases, a high reversible elastic deformation. Thus, they can be also be considered 'biopolymers'. On the other hand, β-keratin has not been investigated as comprehensively. Keratinous materials are strain-rate sensitive, and the effect of hydration is significant. Keratinous materials exhibit a complex hierarchical structure: polypeptide chains and filament-matrix structures at the nanoscale, organization of keratinized cells into lamellar, tubular-intertubular, fiber or layered structures at the microscale, and solid, compact sheaths over porous core, sandwich or threads at the macroscale. These produce a wide range of mechanical properties: the Young's modulus ranges from 10 MPa in stratum corneum to about 2.5 GPa in feathers, and the tensile strength varies from 2 MPa in stratum corneum to 530 MPa in dry hagfish slime threads. Therefore, they are able to serve various functions including diffusion barrier, buffering external attack, energy-absorption, impact-resistance, piercing opponents, withstanding repeated stress and aerodynamic forces, and resisting buckling and penetration. A fascinating part of the new frontier of materials study is the development of bioinspired materials and designs. A comprehensive understanding of the biochemistry, structure and mechanical properties of keratins and keratinous materials is of great importance for keratin-based bioinspired materials and designs. Current bioinspired efforts including the manufacturing of quill-inspired aluminum composites, animal horn-inspired SiC composites, and feather-inspired interlayered composites are presented and novel avenues for research are discussed. The first inroads into molecular-based biomimicry are being currently made, and it is hoped that this approach will yield novel biopolymers through recombinant DNA and self-assembly. We also identify areas of research where knowledge development is still needed to elucidate structures and deformation/failure mechanisms

Human Serum Albumin Binds Native Insulin and Aggregable Insulin Fragments and Inhibits Their Aggregation

The purpose of this study was to investigate whether Human Serum Albumin (HSA) can bind native human insulin and its A13–A19 and B12–B17 fragments, which are responsible for the aggregation of the whole hormone. To label the hormone and both hot spots, so that their binding positions within the HSA could be identified, 4-(1-pyrenyl)butyric acid was used as a fluorophore. Triazine coupling reagent was used to attach the 4-(1-pyrenyl)butyric acid to the N-terminus of the peptides. When attached to the peptides, the fluorophore showed extended fluorescence lifetimes in the excited state in the presence of HSA, compared to the samples in buffer solution. We also analyzed the interactions of unlabeled native insulin and its hot spots with HSA, using circular dichroism (CD), the microscale thermophoresis technique (MST), and three independent methods recommended for aggregating peptides. The CD spectra indicated increased amounts of the α-helical secondary structure in all analyzed samples after incubation. Moreover, for each of the two unlabeled hot spots, it was possible to determine the dissociation constant in the presence of HSA, as 14.4 µM (A13–A19) and 246 nM (B12–B17). Congo Red, Thioflavin T, and microscopy assays revealed significant differences between typical amyloids formed by the native hormone or its hot-spots and the secondary structures formed by the complexes of HSA with insulin and A13–A19 and B12–B17 fragments. All results show that the tested peptide-probe conjugates and their unlabeled analogues interact with HSA, which inhibits their aggregation

Search for New Aggregable Fragments of Human Insulin

In this study, three independent methods were used to identify short fragment of both chains of human insulin which are prone for aggregation. In addition, circular dichroism (CD) research was conducted to understand the progress of aggregation over time. The insulin fragments (deca- and pepta-peptides) were obtained by solid-phase synthesis using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate (DMT/NMM/TosO-) as a coupling reagent. Systematic studies allowed identification of the new fragments, expected to be engaged in triggering aggregation of the entire structure of human insulin under physiological conditions. It was found that the aggregation process occurs through various structural conformers and may favor the formation of a fibrous structure of aggregate

Conjugates of Chitosan and Calcium Alginate with Oligoproline and Oligohydroxyproline Derivatives for Potential Use in Regenerative Medicine

New materials that are as similar as possible in terms of structure and biology to the extracellular matrix (external environment) of cells are of great interest for regenerative medicine. Oligoproline and oligohydroxyproline derivatives (peptides 2–5) are potential mimetics of collagen fragments. Peptides 2–5 have been shown to be similar to the model collagen fragment (H-Gly-Hyp-Pro-Ala-Hyp-Pro-OH, 1) in terms of both their spatial structure and biological activity. In this study, peptides 2–5 were covalently bound to nonwovens based on chitosan and calcium alginate. Incorporation of the peptides was confirmed by Fourier transform -infrared (FT-IR) and zeta potential measurements. Biological studies (cell metabolic activity by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and Live/Dead assay) proved that the obtained peptide-polysaccharide conjugates were not toxic to the endothelial cell line EA.hy 926. In many cases, the conjugates had a highly affirmative influence on cell proliferation. The results of this study show that conjugates of chitosan and calcium alginate with oligoproline and oligohydroxyproline derivatives have potential for use in regenerative medicine

Self-Association of Amphotericin B: Spontaneous Formation of Molecular Structures Responsible for the Toxic Side Effects of the Antibiotic

Amphotericin B (AmB) is a lifesaving antibiotic used to treat deep-seated mycotic infections. Both the pharmaceutical activity and highly toxic side effects of the drug rely on its interaction with biomembranes, which is governed by the molecular organization of AmB. In the present work, we present a detailed analysis of self-assembly of AmB molecules in different environments, interesting from the physiological standpoint, based on molecular spectroscopy techniques: electronic absorption, circular dichroism, steady state and time-resolved fluorescence and molecular dynamic calculations. The results show that, in the water medium, AmB self-associates to dimeric structures, referred to as “parallel” and “antiparallel”. AmB dimers can further assemble into tetramers which can play a role of transmembrane ion channels, affecting electrophysiological homeostasis of a living cell. Understanding structural determinants of self-assembly of AmB opens a way to engineering preparations of the drug which retain pharmaceutical effectiveness under reduced toxicity